Recently, using word processors, personal computers, etc., plotting/editing of characters, images, etc., are permitted using a pen input interface such as a stylus pen, a tablet, etc., with simple and easy operation by means of a pen. However, most pen input interfaces available on the market do not have a tool force detecting function, and the effective use of the tool force detecting function has not yet been spread.
There are known techniques of varying a width of a line or a size of a dot for plotting based on a level of a tool force, and techniques of selecting an object to be edited based on a level of a tool force, etc. With the conventional techniques, the tool force is in proportion to the width of a line for plotting, and a plotting can be performed using a line of a variable width by adjusting a tool force.
Such conventional techniques are known, for example, from Japanese Laid-Open Patent Application No. 279980/1992 (Tokukaihei 4-279980) wherein a plurality of different objects or windows are selected based on a level of tool force detected by a tool force detecting device. In the device of this citation, an image is plotted by controlling a transmissivity to color used in plotting based on a level of a tool force, a mixed ratio of a color used in a background to a color used in plotting an image is adjusted to form a natural image like a recoating in a watercolor painting.
Another technique is disclosed in Japanese Laid-Open Patent Application No. 282094/1993 (Tokukaihei 5-282094), wherein a handwritten input can be made as if human being actually plots a line or a point by varying a width of a line or a size of a dot according to the level of tool force.
A still another technique is disclosed in Japanese Laid-Open Patent Application No. 195938/1983 (Tokukaisho 58-195938), wherein an expanded information can be inputted according to the tool force. In the arrangement of this citation, the user can lock the expansion when the information is displayed in a desired enlarged scale by applying a tool force to a light pen while observing a screen on the CRT. Additionally, a circle can be plotted by inputting a radius and a center of the circle by specifying a compass.
However, none of the above-described citations disclose a technique of instantaneously confirming the level of the tool force being applied by the user with a pen. Namely, the conventional document processing devices require a resulting plotting of a line by moving the pen to be determined based on the thickness of the line, and also requires the level of the tool force to be adjusted manually. On the other hand, Japanese Laid-Open Patent Application No. 195319/1992 (Tokukaihei 4-195319) discloses a light emitting display section for informing a state of a tool force based on a brightness. However, the citation does not provide a sufficient solution to recognize a tool force during a plotting operation performed by the user.
Besides, according to the described arrangement, when the user does not wish to vary the width of the line, etc., according to the level of the tool force, it is required to switch an operable mode between a mode in which a tool force is detected and a mode in which a tool force is not detected. To perform such switching of the operational mode, a troublesome operation is required, such as removing a pen from the current position to select a menu or an icon, etc. Moreover, Japanese Laid-Open Patent Application No. 195938/1983 (Tokukaisho 58-195938) fails to disclose operation means for locking the expansion in a desired enlarged scale. Such operation means is obtainable with ease, for example, by forming a lock instruction key on the keyboard, or forming a switch attached to a pen, etc. In the former case; however, it is required to operate a key on the keyboard with a hand which does not hold a pen as the other hand is occupied with the pen, thereby presenting a drawback of low operability. On the other hand, when adopting the latter case, a cost of manufacturing the device would be increased.
Additionally, there are known editing technique based on borders such as an image border, a graphic border, a character border, etc. However, the technique of scaling such borders as a whole has not yet been proposed. For example, although Japanese Laid-Open Patent Application No. 119415/1991 (Tokukaisho 3-119415) teaches the arrangement for scaling graphics, the technique adopted therein is not based on borders.